Materials Literature
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Full spectral details in support of the earlier proposed structure 1a for the antitumor antibiotic ravidomycin are presented together with an account of chemical degradation products. A complete corroboration of structure is provided by cross correlation of 1 H and 13 C nmr for ravidomycin and its diacetate 1b.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMolecular mobilities of individual constituent carbons of solid polyesters above Tg as studied by carbon-13 nuclear magnetic resonance spectroscopyFumitaka Horii, Asako Hirai, Kouichi Murayama, Ryozo Kitamaru, and Toshimitsu SuzukiCite this: Macromolecules 1983, 16, 2, 273–2…
Magnetically induced birefringence measurements were performed in the isotropic phase of methoxybenzylidene butylaniline (MBBA). Over the entire temperature range studied, $\ensuremath{\Delta}n$ was found to be linear in ${H}^{2}$ to fields over 10 T. This result is consistent with the Landau model of the nematic-isot…
Zigzag propagation of deformation microtwins across the domain structure, as observed by electron microscopy in ordered Ni3V alloy, is shown to be due to cross-slip of partial dislocations via the stair-rod mode (Fleischer 1959). Twin bands change direction to preserve the long-range order inside domains. The peculiar…
<div class="htmlview paragraph">Structural ceramic components have been successfully operated in a diesel engine. The pistons, liner, and housing for an opposed piston, two-cycle (valveless) engine were fabricated from sintered alpha SiC. The ceramic engine was tested without any lubrication or cooling in the cy…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSelective ring-opening polymerization of 1,4-anhydro-2,3-di-O-benzyl-α-D-xylopyranose and synthesis of stereoregular (1 → 5)-.alpha.-D-xylofurananToshiyuki Uryu, Junichi Yamanouchi, Shuji Hayashi, Hidehiko Tamaki, and Kei MatsuzakiCite this: Macromolecules 1983, 16, 2, 320–3…
Abstract Copolyimides, their microstructure being determined by the method of synthesis, were prepared by copolycondensation of 4,4′‐oxydiphthalic anhydride (1a) , 4,4′‐carbonyldipthalic anhydride (1b) , or 1,8:4,5‐naphthalenetetracarboxylic anhydride with a mixture of two diamines, hexa‐, octa‐, or dodecamethylene di…
<div class="htmlview paragraph">Monolithic ceramic filters, suitable for reducing particulate emissions to within the 0,2 g/mile emissions limit, are intermittantly loaded and regenerated. A mathematical model was developed in order to describe the processes which take place in the filter during regeneration. Th…
Bond-orientational order in materials that form three-dimensional uniaxial solids is investigated. New phases are found that scatter light strongly, like nematics, but with a quantitatively different anisotropy of scattering. X-ray scattering from these phases would also exhibit novel anisotropy. This type of order ma…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSmog chamber studies of nitrogen oxide (NOx) transformation rate and nitrate precursor relationshipsChester W. SpicerCite this: Environ. Sci. Technol. 1983, 17, 2, 112–120Publication Date (Print):February 1, 1983Publication History Published online1 May 2002Published inissue…
An improved cube method was developed for the computation of X-ray scattering curves of macromolecules in solution. For double-helical DNA and RNA molecules the efficiency of this method is shown. The results are compared with curves calculated by effective atomic scattering factor methods. In the small-angle and in t…
In vitro corrosion of Cu-rich amalgams resulted in selective attack of the η' phase. Copper was removed, and SnO 2 products were found in pores and along matrix grain boundaries. The corrosion process greatly accelerated the γ 1 →β 1 transformation.
Abstract Saponite crystallizes from amorphous gel having an ideal saponite composition within 7 days at all experimental temperatures between 300° and 550°C at 1 kbar pressure. Reactions subsequent to this initial crystallization vary in type and degree, depending on the temperature of reaction and the type of interla…
Single-crystal X-ray analysis (R 1 = 0.030, R 2 = 0.031) in space group Cc. On a statistical basis, the M(1) site (mean M(1)-O = 2.14Aa) contains 0.55 Li and 0.45 vacancy, whereas the M(2) and M(3) sites (mean M(2)-O, = 1.902,M(3)-O = 1.903Aa) are fully occupied by Al. In the tetrahedral sites, the ordering of Al,Be r…
In connection with recently published work on the ternary system Ni–Al–Ta two binary alloys were produced for investigation. A Ni–31 at.-%Al alloy was prepared in order to assess the accuracy of the microprobe analysis technique by analysing an alloy heat treated to produce a single phase structure and comparing this…
A consistent quantum-mechanical description is given of some atomistic properties of hydrogen isotopes in bcc metals, including in particular the energy and wave functions of a hydrogen atom, its preference of the type of interstitial sites, distortion of the surrounding lattice, and its effects on crystal structure.…
A method for making low-voltage ZnO varistors having extraordinarily large grain size without necessity of sintering at much higher temperatures or for much longer times is reported. The device is made by sintering a mixture of ZnO fine powder, additives, and ZnO seed grains having grain sizes of 63–105 μm obtained by…
Abstract A previous paper described an unusual crystallinity effect observed in ultrahigh molecular weight linear polyethylene (UHMW PE) and conventional high density polyethylene (HDPE). It was discovered that upon exposure to high energy radiation, these polymers experience a significant increase in the degree of cr…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolymer-supported membranes. A new approach for modifying polymer surfacesSteven L. Regen, Piotr Kirszensztejn, and Alok SinghCite this: Macromolecules 1983, 16, 2, 335–338Publication Date (Print):February 1, 1983Publication History Published online1 May 2002Published inissu…
Internal defects and twin structures exist in thermally transformed monoclinic ( m )‐ZrO 2 particles confined in a mullite matrix. The defects were analyzed by transmission electron microscopy. Twin boundaries on (100), (110), (001), and (011) were found. Frequently, (100) and (110) twins formed complicated mosaiclike…